1. Field of the Invention
This invention relates to a knob-like tool for attachment to a medical guidewire as used, for example, to guide a catheter into an artery or arterial branch to a stenosis or partial blockage position where vessel enlargement is performed with an angioplasty balloon.
2. The Prior State of the Art
The use of guidewires in catheterization and angioplasty procedures is well known, and is further described in issued patents such as U.S. Pat. No. 4,957,117.
The guidewire is long (typically six feet or more of stainless steel wire) and slender with a relatively limber and bendable distal tip which can be angled to assist the physician in negotiating arterial curves and junctions to the desired location by fluoroscopic monitoring.
The surface of the slender guidewire is smooth and slick, and some kind of auxiliary gripping surface is needed to enable the wire to be advanced into or retracted from the arterial vessels, and especially to enable twisting or torquing rotation of the wire as needed to reorient the angled distal tip. Existing partial solutions to this need include pin-vise grips.
A pin-vise is a device that is well known in the art and which comprises a structure like a small drill chuck with a cylindrical handle. The chuck is threaded over the proximal end of the long guidewire and advanced to a desired position. A chuck collet, a part of the pin-vise, can then be tightened onto the wire so that the pin-vise is firmly attached to the guidewire, and thereafter serves as a grip to facilitate manual rotation of the guidewire and/or longitudinal advancement of the same.
One of the problems which has been experienced in the art using pin-vise type grips is that they must be threaded onto the guidewire at the proximal end. This is time consuming and inconvenient because of the length of the guidewire. Thus, other types of gripping devices have been devised which attempt to overcome this problem.
One such gripping device is illustrated, for example, in U.S. Pat. No. 4,829,999. This device is constructed with a cylindrical body which has a longitudinal slit and which is spring-actuated so that by pressing two handles together which are provided on the body of the device, the longitudinal slit can be opened and placed onto the guidewire. When the handles are released, the resilient or spring-action of the cylindrical body clamps the guidewire within the longitudinal slit, much like clamping a clothespin into a clothesline.
This device overcomes the problem of having to thread the device onto the proximal end of the guidewire, but suffers from other disadvantages. For example, the handles which are located on the side of the cylindrical body may get in the way of rotational manipulation of the device. Furthermore, it is typically necessary to reposition a gripping device on a guidewire as the guidewire is advanced further into the vessels. Thus, the side mount type gripping device as described for example in the above referenced patent requires that the device be taken off and repositioned on the guidewire. If the device is dropped while taking it off, it becomes unsterile and must be replaced.
Another device which has attempted to address the problems in the art is illustrated, for example, in U.S. Pat. No. 4,858,810. This device utilizes a pin-vise constructed from two parts assembled together to provide a gripping handle for a guidewire. The device has an elongated cylindrical body which is slotted along the length to receive the guidewire, and also has a sliding mechanism which fits within the slot and which, when pushed forward, tightens down upon the guidewire in order to secure the gripping device to the guidewire for purposes of manipulation. As in the case of the spring-actuated type gripping device described above, this device is also a side-mount type device, which eliminates the need for threading the device onto the proximal end of the guidewire. However, the placement of the device onto the guidewire is somewhat cumbersome and if the cylindrical body member is inadvertently dropped before the slide mechanism is placed into the longitudinal slot, once again the device may become unsterile. Another example of a device that utilizes a slide mechanism is that described in U.S. Pat. No. 5,159,861.
Still a further device which is known in the art is a side loading type of gripping device which, once again, employs a longitudinal slot along the length of the device, and which includes two cylindrical members that are threaded together. The distal end of one of the cylindrical members is formed with a plurality of fingers so that as the two members are threaded together the fingers clamp down and grip the guidewire. This device, like the others, partially solves some of the problems experienced in the art, but is otherwise more complicated in its construction and cumbersome to operate than is desirable.